Updated at 5:34 p.m. ET on March 11, 2021.
If you’ve read Malcolm Gladwell’s Outliers, you probably remember the argument he makes in the book’s first chapter: In competitive situations, a person who’s relatively older than the others will probably be the one who wins.
Gladwell centers on a real-world example in which almost all of the players who had been selected for a Canadian Hockey League team had birthdays in the first four months of the year. Why? In Canada, Gladwell reasons, the cut-off age for participating in the sport is almost always January 1. A child who, say, turns 11 on January 4 would still play alongside a child who turns 11 much later in the year—and at that stage in life, there are typically significant distinctions in physical characteristics and abilities between two such kids. Gladwell concludes that in Canada, the world’s hockey capital, this policy puts the two children on two very different paths from the get go; the older, more physically developed one gets selected for all-star teams, which means better coaching, resources, and practice opportunities, and, ultimately, a better shot at the pros.
This phenomenon, according to the 2008 book, extends far beyond Canada and hockey. Hence, Gladwell’s famous case for academic redshirting: the increasingly popular parental practice of delaying kids’ entrance into kindergarten. According to some research, between 4 percent and 9 percent of kindergartners are redshirted annually. And while some scholars have suggested that redshirting doesn’t do much of anything—at least in the long run—Gladwell contends that this assumption is false. Rather, this dynamic persists in insidious ways, locking “children into patterns of achievement and underachievement, encouragement and discouragement, that stretch on and on for years,” he writes, pointing to a widely cited 2006 study that found that cut-off dates can even have an impact on whether or not a child ends up going to college.